Rover ST-4 Survey Instrument Replacement Battery 7.2V 3500mAh

Rover Instruments ST-4 / DM16C / DM16Q — 7.2V Ni-MH Replacement Battery (BAT-PACK-ST4-DM16)

This is a 7.2V 3500mAh Ni-MH replacement battery for the Rover Instruments ST-4, DM16C, DM16Q, and HD ProTab series survey instruments. It matches the OEM part number BAT-PACK-ST4-DM16 and slots directly into the battery compartment on each listed model. Capacity is 3500mAh (25.2Wh), drawn from the product specification — not estimated.

• ST-4, DM16C, DM16Q, and HD ProTab compatibility: These models share the same 7.2V battery rail, connector pinout, and BMS handshake protocol. A single pack covers the full listed range without modification or adapter.
• Bench tested on actual hardware: We cycled this pack through the instrument's initialisation sequence and sustained sensor logging load. The BMS held stable across repeated probe power-up spikes and did not trip into protection mode under normal field draw.
• First-use calibration on the ST-4 and DM16 series: After fitting a new pack, run a full calibration cycle through the instrument menu before heading into the field. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during your first measurement session, even with a fully charged pack.

BMS lockout on the ST-4 after the pack sat unused in a carry case for months

Ni-MH cells self-discharge slowly during storage. If the pack voltage drops below roughly 5.5V across the cell string, the protection circuit enters sleep mode and blocks charge input. The instrument will show no charging activity and may not power on at all. To recover, apply a slow trickle charge at 0.1C directly to the pack for 15–20 minutes to raise the cell voltage above the BMS wake threshold — then resume normal charging through the instrument's dock or charger.

Readings resetting or data logging dropping mid-session on the DM16C and DM16Q

This happens when sustained sensor load pulls cell voltage below the instrument's dropout threshold — typically around 6.0V under load on a degraded or partially charged pack. The instrument interprets the voltage sag as a critical power event and resets the active logging session to protect stored data. It is not a firmware fault. Charge the pack to full before a logging-heavy session, and check that cell voltage under load stays above 6.2V using the instrument's onboard voltage readout in the diagnostics menu.